RU2718762C1 - Method of producing ethylene from renewable non-food vegetal raw materials - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to a method for production of ethylene from renewable vegetal raw materials without food value. Disclosed is a method of producing ethylene from renewable non-food vegetal raw materials, which includes grinding raw material, preliminary chemical treatment with 3–6 % nitric acid solution at 90–95 °C and atmospheric pressure for 3–6 hours, preliminary saccharification is carried out for 18–24 h, combined saccharification and fermentation process, obtaining a fermentable wort as result, which is subjected to distillation and obtaining ethanol with concentration of 90–96 wt%, which contains impurities in terms of anhydrous ethanol C3 alcohols of not more than 7 g/l, sodium ions of not more than 0.01 mg⋅eq/l, the obtained product – ethanol is fed into a catalytic reactor, where it is dehydrated to obtain a reaction gas containing ethylene, residual ethanol and water vapor, from which the gaseous phase of ethylene is separated, and produced after ethanol dehydration reactor liquid phase containing water with residual ethanol dissolved in it, mixed with fermentable wort flow and directed for distillation, and waste of alcohol production – spent wash – is supplied for burning and generation of heat, with its subsequent use in endothermic process of ethanol dehydration into ethylene.

EFFECT: production of ecologically clean and economically attractive high-demand product – ethylene.

4 cl, 1 dwg, 16 ex

Description

The invention relates to a method for producing ethylene from non-renewable plant materials without food value.

Ethylene, obtained from fossil hydrocarbon feedstocks, is a large-capacity petrochemical semi-product used to produce more than 75% of valuable chemical products. Currently, methods for producing ethylene from alternative renewable raw materials are being intensively developed, including biotechnological stages of ethanol production and catalytic stages of its conversion to ethylene. However, existing technologists use high-value raw materials for food purposes (sugarcane, corn, wheat grain and others), which when applied on a large scale creates serious agricultural and ethical problems. In this regard, the development of technologies for obtaining valuable chemical products based on plant materials that are not of food value is relevant. Of particular interest among cellulose-containing biomass are industrial crops of the cereal family and massive agricultural waste. Miscanthus is characterized by high productivity even on poor soils and high storage stability, this ensures a stable quality of raw materials and stable operation of biotechnological production. Oat fruit shells are a unique type of reproducible raw material, they make up 28% of the grain mass and accumulate on an industrial scale at grain processing enterprises.

The prior art method for producing ethylene from ethanol or ethanol feedstock (US 20090008610 A1, B82Y 40/00, 8.01.2009). The disadvantage of this method is the use of valuable food raw materials for industrial products; in addition, information about ethanol quality requirements, the presence of organic or inorganic impurities in it is not disclosed, but the need for an expensive stage of ethanol purification is noted.

Known methods for the dehydration of ethanol to ethylene (RU 2597422, C07C 1/24, 09.07.2012; RU 2415121, C07C 1/24, 11.2.2006), in which the reaction is carried out in a reactor under pressure, and the dehydration waste: water, remaining ethanol or After separation and purification, diethyl ether is partially recycled back to the reactor, thereby obtaining diluted ethanol at the inlet of the reactor. The disadvantage of such methods is the use of complex and costly stages of separation and purification of water, residual ethanol or diethyl ether, as well as the low efficiency of the use of equipment during the dehydration of ethanol diluted with water.

Known (RU 2701643, С12Р 7/06, 09/09/2018, RU 2593724, С12Р 7/06, 06/25/2015)

Methods for producing ethanol from cellulose-containing biomass (Miscanthus, fruit shells of oats, etc.). The disadvantage of such methods is that only one grade of Miscanthus is used as a raw material in the technology, despite the existence of more than 14 varieties growing in different climatic regions. A significant drawback is that waste and effluent from alcohol production - stillage and water after distillation of ethanol - are not used, which requires the cost of their disposal. The patent does not disclose the quality of the ethanol obtained, in particular, there are no quantitative data on the content of organic and inorganic impurities, although the impurities in ethanol can be crucial for the profitability of the production of valuable chemical products based on it.

The prior art method for the production of ethylene (olefins) (application WO 2008/067627 A3, C07C 11/04, 12/05/2006), from plant materials, including grinding raw materials, obtaining mash, followed by distillation to ethanol and its dehydration to ethylene in reactors with a stationary catalyst bed, where steam in the ratio 2: 1 to the mass of alcohol is supplied as a heat carrier for the endothermic reaction, while the steam used in the endothermic process of ethanol dehydration is generated as a result of the burning of waste from alcohol production - vinasse. The proposed method has the following disadvantages: the use of food raw materials (sugar cane, corn), the low completeness of the processing of ethanol in the process of its dehydration into ethylene; low efficiency of use of equipment in the dehydration of ethanol diluted with water vapor.

As a prototype, a method for producing ethylene from non-food raw materials - oat husks (fruit shells of oats) was chosen (Skiba E.A. et al. Pilot Technology of Ethanol Production from Oat Hulls for Subsequent Conversion to Ethylene // Chemical Engineering Journal. 2017. V . 391. P. 178-186. Https://doi.Org/10.1016/j.cej.2017.05.05.182), which includes the preliminary chemical treatment of vegetable raw materials - oat husks, the combined process of saccharification (enzymatic hydrolysis) and alcohol fermentation to obtain mash, distillation to isolate ethanol, dehydration of ethanol and its purification, catalytic dehydration of ethanol to ethylene. The ethylene yield is less than 42 kg / t of biomass. A significant drawback of the method is that a reagent (sodium hydroxide) is used at the biomass pretreatment stage, the residual content of Na ions from which in ethanol leads to a loss of catalyst activity and a low yield of ethylene, therefore, before the catalytic dehydration of ethanol into ethylene, it will additionally require washing and re-distillation . The lack of technological integration of flows between the stages of ethanol production from biomass and its dehydration into ethylene, as well as the presence of additional stages leads to the formation of a large number of effluents that require disposal.

The invention solves the problem of involving in the economic turnover of alternative raw materials, namely, cheap readily renewable biomass of non-food purposes, in order to obtain a highly demanded product, ethylene, using environmentally friendly and economically attractive technology.

The problem is solved by the proposed method for the production of ethylene from non-renewable plant raw materials, which includes: grinding of raw materials, preliminary chemical treatment, preliminary saccharification for 18-24 hours, the combined process of saccharification and alcohol fermentation, to obtain mash, which is subjected to distillation, and the obtained ethanol sent to a catalytic reactor, where the process of dehydration of ethanol into ethylene takes place, while the preliminary chemical processing of the feedstock is carried out yayut nitric acid solution having a concentration of 3-6% at atmospheric pressure, the distillation is carried out until the mash ethanol content 90-96 wt. %, the content of C3 impurities of alcohols (propanol and isopropanol) is not more than 7 g / l, and preferably not more than 3.5 g / l, preferably not more than 0.7 g / l, but not less than 0.1 g / l, when the content of sodium ions in the feed does not more than 0.01 mg equivalent / liter calculated on anhydrous ethanol, and the ethanol obtained is sent to catalytic dehydration to obtain a reaction gas containing ethylene, residual ethanol and water vapor, after which the products are separated, and the gas phase of ethylene is sent to consumers, and the liquid a phase containing water with residual ethanol dissolved in it, meshivayut a mash stream and directed to distillation, and the waste of alcohol production - the burning of vinasse is directed to the generation of heat, which is subsequently used in an endothermic process of dehydration of ethanol to ethylene.

As a raw material, Miscanthus is used, which includes approximately 14-20 species, including Miscanthus sacchariflorus, Miscanthus sinensis Anderss., Miscanthus purpurascens Anderss., As well as Miscanthus giganteus, which are a practically inexhaustible source of non-food non-renewable raw materials in the field of alternative energy.

As raw materials, fruit shells of oats are used, which are a waste of agricultural production; the attractiveness of their use is due to the low cost, since the costs of cultivation are fully paid off by the products of oat processing.

As a raw material, you can use any mixture of various types of Miscanthus, as well as a mixture of Miscanthus with fruit shells of oats in any percentage.

The environmental attractiveness of the technology is due to the use of renewable raw materials, the secondary use of waste, the absence (or small amount) of effluents and waste, the high efficiency of processing raw materials into target products and the small amount of by-products.

The present invention differs from the prototype in that the preliminary chemical treatment is carried out with a solution of nitric acid with a concentration of 3-6% at atmospheric pressure for 3-6 hours, and the distillation of the mash is adjusted to an ethanol content of 90-96 wt. %: the process is carried out so that the content of C3 impurities of alcohols (propanol and isopropanol) is (calculated on anhydrous ethanol) not more than 7 g / l, and preferably not more than 3.5 g / l, preferably not more than 0.7 g / l, but not less than 0.1 g / l, and the content of sodium ions - not more than 0.01 mg · equivalent ../ l calculated on anhydrous ethanol; the ethanol obtained is sent to catalytic dehydration to obtain a reaction gas containing ethylene, residual ethanol and water vapor, after which the products are separated, and the gas phase of ethylene is sent to consumers, and the liquid phase containing water with the residual ethanol dissolved in it is mixed with the mash stream and sent to distillation, and the waste of alcohol production - bard - is sent to combustion with heat generation, which is subsequently used in the endothermic process of ethanol dehydration to ethylene, and as an easily renewable non-food plant material for the production of ethylene, in addition to the fruit shells of oats, different varieties of miscanthus and their mixtures are used.

The present invention implements an environmentally friendly closed loop technology. It uses waste from alcohol production - bard and water after distillation of the mash, waste from the production of ethylene - water with residual ethanol dissolved in it. This allows for technological integration of flows, to reduce energy costs for the endothermic process of producing ethylene, to achieve high completeness of the use of biomass, ethanol and water, to eliminate the formation of effluents and waste. In the absence of technological integration of waste from the production of alcohol and ethylene, energy costs increase, the completeness of processing biomass, ethanol and water decreases, and effluents and waste appear.

The method of producing ethylene according to the invention is as follows (see drawing).

As raw materials use miscanthus (1), which after harvesting (2) is subjected to grinding (3). Next, a 3-6% solution of nitric acid (5) is prepared from water (21) and nitric acid (4) and the miscanthus is pretreated with this solution at atmospheric pressure (6). At the end of the preliminary chemical treatment, a cellulose-containing product (7) is obtained, which is used for preliminary saccharification (8) using enzyme preparations (9). After preliminary saccharification for 18-24 hours, a hydrolyzate (10) is obtained, into which the ethanol producer (I) is added and a combined process of saccharification and alcoholic fermentation (12) is carried out, as a result of which a mash is obtained (13) and the distillery waste - bard ( 19). The obtained mash (13) is subjected to distillation (14), as a result of which water (21) is isolated and ethanol (15) is obtained with a purity of 90-96 wt. % with an impurity content of C3 alcohols of not more than 7 g / l, and preferably not more than 3.5 g / l, preferably not more than 0.7 g / l, but not less than 0.1 g / l, with a content of sodium ions in the feed not more than 0.01 mg eq ./l calculated on anhydrous ethanol. Ethanol (15) is used in the endothermic process of catalytic dehydration into ethylene on an alumina catalyst at a temperature of 375-400 ° С, a gas load of ethanol on a catalyst (G) of 9400-10800 1 / h and a pressure of 0.11 MPa (16). As a result of the catalytic dehydration of ethanol (16), the target product is obtained - ethylene (17), as well as water with an admixture of residual ethanol (18). The resulting water with an admixture of residual ethanol (18) together with the mash (13) is fed to distillation (14). Barda (19) is directed to combustion with the generation of heat (20), which is used in the endothermic process of catalytic dehydration of ethanol (16). Water (21) obtained in the process of distillation (14) is used to obtain a 3-6% solution of nitric acid (5).

The gas load on the catalyst (G) is defined as the ratio of the hourly flow rate of the ethanol gas stream at the inlet of the reactor (l / h) to the volume of the catalyst (l). The completeness of ethanol processing is defined as the ratio of the difference between the mass of 100% ethanol fed to the reactor and the mass of residual ethanol contained in unused waste after the catalytic dehydration reactor, to the mass of ethanol fed to the reactor (in the case of waste, there are no emissions of ethanol, and the completeness of ethanol processing is 100 %). The ethylene yield per unit mass of biomass is defined as the ratio of the mass of ethylene produced to the mass of spent biomass. The determination of these indicators was performed based on 100% ethylene.

The method of producing ethylene according to the invention is illustrated by the following examples:

Example 1. Comparative

The biomass of Miscanthus sacchariflorus with a moisture content of 35% under experimental production conditions is subjected to chemical treatment with a solution of sodium hydroxide with a concentration of 2% at a temperature of 80 ° C for 1 h, then washed until neutral. Pre-saccharification is carried out at a temperature of 47 ° C and an active acidity of 3.5 units. pH The enzymatic preparations “Cellolux-A” and “Bruzime BGX” contribute 0.02 g of enzyme per 1 g of substrate. The duration of preliminary saccharification is 14 hours. Then, the enzymatic hydrolyzate is cooled to 30 ° C, sowing yeast Saccharomyces cerevisiae is introduced in an amount of 10%, and alcohol fermentation combined with saccharification is carried out for 72 hours. The resulting mash is subjected to distillation with the release of ethanol with a purity of 87.0 wt. % with a C3 content of alcohols of 7.8 g / l and sodium ions of 0.6 mg equivalent / l, calculated on anhydrous ethanol. Waste from alcohol production is formed - bard and water after distillation.

Ethanol with a purity of 87.0 wt. % with a C3 content of alcohols of 7.8 g / l and sodium ions of 0.6 mg eq./l are sent to a catalytic reactor in which at a temperature of 400 ° C, the gas load of ethanol on an alumina catalyst (G) 11130 1 / h and At a pressure of 0.11 MPa, the endothermic process of dehydration of ethanol into ethylene proceeds to which external heat is supplied. As a result of the catalytic reaction, the target product is obtained - ethylene, as well as water with residual ethanol dissolved in it. Ethylene is sent to the consumer. Runoffs of the catalytic process are formed - water with residual ethanol dissolved in it.

The yield of ethylene per 1 ton of biomass is 47 kg per 1 ton of miscanthus, the completeness of ethanol processing is 86%.

Example 1 demonstrates that the production of ethanol from non-renewable non-food plant materials during its preliminary chemical treatment with sodium hydroxide under conditions close to the prototype, there is a high content of C3 alcohols and sodium ions in ethanol, which leads to a low yield of ethylene due to the deactivation of the ethanol dehydration catalyst in the presence of a high content of C3 alcohols and sodium ions.

Example 2. Comparative

The process is carried out as in example 1, but the preliminary chemical treatment is carried out with a solution of nitric acid with a concentration of 2%, for the preparation of which use slightly demineralized water; the result is bioethanol with a purity of 86.1 wt. % with a C3 content of alcohols of 7.5 g / l and sodium ions less than 0.05 mg eq / l; catalytic dehydration of ethanol is carried out at G = 11260 1 / h

The yield of ethylene per 1 ton of biomass is 68 kg per 1 ton of miscanthus, the ethanol processing is 88% complete.

Example 2 demonstrates that pre-treatment of biomass with nitric acid virtually eliminates the content of sodium ions in the resulting ethanol, but due to the use of insufficient desalted water for the preparation of a weak acid solution, Na is present in a noticeable amount; as well as when performing this treatment under conditions close to the prototype, namely, at a low acid concentration, low temperature and duration of chemical treatment and preliminary saccharification, there is a low purity of ethanol, a high content of C3 alcohols in it, which leads to a low yield of ethylene from the low activity of the catalyst for the dehydration of ethanol in the presence of a high content of C3 alcohols and sodium ions; in addition, due to the lack of technological integration of flows and the secondary use of waste (examples 1 and 2): stillage (waste from alcohol production), water after distillation of the mash, water with residual ethanol dissolved in it after the catalytic process, there are drains and waste, as well as additional energy costs for the implementation of the endothermic catalytic process. Example 3

The process is carried out as in example 2, but a preliminary chemical treatment is carried out with nitric acid with a concentration of 3% at a temperature of 90 ° C for 5 hours; the duration of preliminary saccharification is 18 hours; the result is bioethanol with a purity of 92.5 wt. % with a C3 content of alcohols of 0.71 g / l and sodium ions of less than 0.01 mg eq./l.

Water after the distillation stage is sent to the preparation of a weak solution of nitric acid for preliminary chemical treatment of biomass.

The waste from alcohol production - bard - is sent to combustion with heat generation for its use in the endothermic process of ethanol dehydration to ethylene.

Ethanol with a purity of 92.5 wt. % with a C3 content of alcohols of 0.71 g / l and sodium ions of less than 0.01 mg eq./l are sent to a catalytic reactor in which the endothermic process of ethanol dehydration proceeds with an ethanol gas load on the alumina catalyst (G) 9400 1 / h in ethylene, the heat to which is supplied by burning the stillage. As a result of the catalytic reaction, the target product is obtained - ethylene, as well as water with residual ethanol dissolved in it. Ethylene is sent to the consumer.

The yield of ethylene per 1 ton of biomass is 96 kg per 1 ton of miscanthus, the completeness of ethanol processing is 94%.

Example 4

The process is carried out as in example 3, but after the catalytic process, water with residual ethanol, together with the mash, is sent to distillation with an ethanol yield of 92.5 wt% purity. % with a C3 content of alcohols of 0.71 g / l and sodium ions of less than 0.01 mg eq./l.

The yield of ethylene per 1 ton of biomass is 102 kg per 1 ton of miscanthus, the completeness of ethanol processing is 100%.

Example 5

The process is carried out as in example 4, but the raw material is the biomass of the fruit shells of oats with a moisture content of 37%, preliminary chemical treatment is carried out with a solution of nitric acid with a concentration of 4% at a temperature of 92 ° C for 3 hours; the duration of preliminary saccharification is 24 hours; the result is bioethanol with a purity of 90.0 wt. % with a C3 content of alcohols of 0.42 g / l and sodium ions of less than 0.01 mg equivalent / l; catalytic dehydration of ethanol is carried out at G = 10760 1 / h.

The yield of ethylene per 1 ton of biomass is 120 kg per 1 ton of fruit shells of oats, the ethanol processing is 100% complete.

Example 6

The process is carried out as in example 5, but the raw material is the biomass of Miscanthus giganteus with a moisture content of 38%, the preliminary chemical treatment is carried out at a temperature of 93 ° C for 4 hours; the duration of preliminary saccharification is 20 hours; the result is bioethanol with a purity of 93.6 wt. % with a C3 content of alcohols of 0.63 g / l; catalytic dehydration of ethanol is carried out at G = 10350 1 / h.

The yield of ethylene per 1 ton of biomass is 128 kg per 1 ton of miscanthus, the completeness of ethanol processing is 100%.

Example 7

The process is carried out as in example 5, but the moisture content of the biomass is 36%; preliminary chemical treatment is carried out with a solution of nitric acid with a concentration of 6% at a temperature of 91 ° C; the duration of preliminary saccharification is 22 hours; the result is bioethanol with a purity of 96.0 wt. % with a C3 content of alcohols 0.11 g / l and sodium ions less than 0.01 mg eq / l; catalytic dehydration of ethanol is carried out at G = 10090 1 / h.

The yield of ethylene per 1 ton of biomass is 104 kg per 1 ton of fruit shells of oats, the completeness of ethanol processing is 100%.

Example 8

The process is carried out as in example 4, but the raw material is the biomass of Miscanthus sinensis with a moisture content of 34%, the preliminary chemical treatment is carried out with a solution of nitric acid with a concentration of 5% at a temperature of 95 ° C for 6 hours; the duration of preliminary saccharification is 21 hours; the result is bioethanol with a purity of 91.7 wt. % with a C3 content of alcohols of 0.29 g / l and sodium ions of less than 0.01 mg equivalent / l; catalytic dehydration of ethanol is carried out at G = 10560 1 / h.

The yield of ethylene per 1 ton of biomass is 103 kg per 1 ton of miscanthus, the completeness of ethanol processing is 100%.

Example 9

The process is carried out as in example 5, but the biomass humidity is 32%, the preliminary chemical treatment is carried out with a solution of nitric acid with a concentration of 3% at a temperature of 94 ° C for 4 hours; the duration of preliminary saccharification is 19 hours; the result is bioethanol with a purity of 94.2 wt. % with a C3 content of alcohols 0.21 g / l and sodium ions less than 0.01 mg eq / l; catalytic dehydration of ethanol is carried out at G = 10 280 1 / h.

The yield of ethylene per 1 ton of biomass is 137 kg per 1 ton of fruit shells of oats, the ethanol processing is 100% complete.

Example 10

The process is carried out as in example 4, but the raw material is the biomass of Miscanthus purpurascens with a moisture content of 35%, a preliminary chemical treatment is carried out with a solution of nitric acid with a concentration of 6% at a temperature of 93 ° C for 3 hours; the duration of preliminary saccharification is 22 hours; the result is bioethanol with a purity of 92.8 wt. % with a C3 content of alcohols of 0.33 g / l and sodium ions of less than 0.01 mg eq./l; catalytic dehydration of ethanol is carried out at G = 10450 1 / h.

The yield of ethylene per 1 ton of biomass is 138 kg per 1 ton of miscanthus, the completeness of ethanol processing is 100%.

Example 11

The process is carried out as in example 5, but the biomass humidity is 33%, the preliminary chemical treatment is carried out with a solution of nitric acid with a concentration of 5% at a temperature of 90 ° C for 5 hours; the duration of preliminary saccharification is 23 hours; the result is bioethanol with a purity of 93.0 wt. % with a C3 content of alcohols of 0.5 g / l and sodium ions of less than 0.01 mg eq./l; catalytic dehydration of ethanol is carried out at G = 10 410 1 / h.

The yield of ethylene per 1 ton of biomass is 108 kg per 1 ton of fruit shells of oats, the ethanol processing is 100% complete.

Example 12

The process is carried out as in example 8, but with a solution of nitric acid with a concentration of 3% at a temperature of 90 ° C for 3 hours; the duration of preliminary saccharification is 18 hours; the result is bioethanol with a purity of 90.0 wt. % with a C3 content of alcohols of 3.47 g / l and sodium ions of less than 0.01 mg equivalent / l; catalytic dehydration of ethanol is carried out at G = 10760 1 / h.

The yield of ethylene per 1 ton of biomass is 86 kg per 1 ton of miscanthus, the completeness of ethanol processing is 100%.

Example 13

The process is carried out as in example 5, but the preliminary chemical treatment is carried out with a solution of nitric acid with a concentration of 3% at a temperature of 89 ° C; the duration of preliminary saccharification is 18 hours; the result is bioethanol with a purity of 89.9 wt. % with a C3 content of alcohols of 6.84 g / l and sodium ions of less than 0.01 mg equivalent / l; catalytic dehydration of ethanol is carried out at G = 10770 1 / h.

The yield of ethylene per 1 ton of biomass is 93 kg per 1 ton of fruit shells of oats, the completeness of ethanol processing is 100%.

Example 14

The process is carried out as in example 6, but the raw material is a mixture of biomass Miscanthus giganteus and Miscanthus purpurascens in a percentage ratio of 50%, with a moisture content of 36%, the preliminary chemical treatment is carried out at a temperature of 94 ° C for 5 hours; the duration of preliminary saccharification is 19 hours; the result is bioethanol with a purity of 90.7 wt. % with a C3 content of alcohols of 0.63 g / l; catalytic dehydration of ethanol is carried out at G = 10680 1 / h.

The yield of ethylene per 1 ton of biomass is 102 kg per 1 ton of miscanthus, the completeness of ethanol processing is 100%.

Example 15

The process is carried out as in example 10, but the raw material is a mixture of biomass Miscanthus purpurascens and fruit shells of oats in a percentage of 50%, preliminary chemical treatment is carried out with a solution of nitric acid with a concentration of 5% at a temperature of 92 ° C for 3 hours; the duration of preliminary saccharification is 21 hours; the result is bioethanol with a purity of 94.5 wt. % with a C3 content of alcohols of 0.5 g / l and sodium ions of less than 0.01 mg eq./l; catalytic dehydration of ethanol is carried out at G = 10,250 1 / h.

The ethylene yield per 1 ton of biomass is PO kg, the ethanol processing completeness is 100%.

Example 16

The process is carried out as in example 4, but the preliminary chemical treatment is carried out with a solution of nitric acid with a concentration of 7% at a temperature of 96 ° C for 7 hours; the duration of preliminary saccharification is 25 hours; the result is bioethanol with a purity of 95.3 wt. % with a C3 content of alcohols of 6.84 g / l and sodium ions of less than 0.01 mg equivalent / l; catalytic dehydration of ethanol is carried out at G = 8460 1 / h

The yield of ethylene per 1 ton of biomass is 58 kg per 1 ton of miscanthus, the completeness of ethanol processing is 100%.

Examples 4-15 illustrate that the duration of preliminary saccharification (18-24 hours) and the complex of technical methods according to the invention, namely: the use of biomass of miscanthus of different varieties and shells of oats and their mixtures in any percentage, the conditions for the preliminary processing of biomass (concentration of reagent 3 -6%, temperature 90-95 ° C and duration 3-6 hours), ethanol production with a purity of 90-96% in May. with a C3 content of alcohols of not more than 7 g / l, and preferably not more than 3.5 g / l, preferably not more than 0.7 g / l, but not less than 0.1 g / l and sodium ions not more than 0.01 mg eq / l, catalytic dehydration at a gas load on the catalyst 9400-10800 1 / h, the secondary use of alcohol production waste - stillage and water after distillation of the mash, waste from ethylene production - water with residual ethanol dissolved in it - provides a high degree of biomass and ethanol processing, high yield ethylene 86-140 kg per 1 ton of non-renewable non-food of vegetable raw materials, as well as technological integration of flows takes place, which eliminates the formation of effluents and waste, reduces energy costs for the endothermic process of producing ethylene.

The conditions for preliminary chemical treatment (reagent, concentration, temperature, duration) and saccharification (temperature and duration) are determined by the type of raw materials used: miscanthus varieties (examples 4, 6, 8, 10, 12, 14, 16), oat fruit shells (examples 5 , 7, 9, 11, 13), their mixtures (examples 14, 15), and depend on its morphological features, strength, etc.

High trace amounts of sodium ions are present in ethanol as a result of alkaline treatment of biomass with sodium hydroxide, or due to the use of insufficiently demineralized water for the preparation of dilute acid solutions. Although with a Na content of 0.01-0.6 mg equivalent / liter at the biomass pretreatment stage, a neutral pH value of the medium is ensured after the stage of neutralization and washing of ethanol, Na impurities of more than 0.01 mg equivalent / liter have a negative effect on the ethylene production catalyst, reducing the completeness of the conversion of ethanol and the yield of ethylene (example 1-2).

The use of nitric acid at the stage of preliminary chemical treatment (examples 2-16) eliminates the stage of costly washing the mash from inorganic impurities or ethanol from the impurities of sodium ions, and the use of a weak solution of it (3-6%) contributes to low aggressiveness (corrosion activity) of the medium, safety and environmental friendliness of production.

Low acid concentration, low processing time and preliminary saccharification contribute to a low yield and concentration of ethanol, a high content of C3 alcohols (propanol and isopropanol), due to the low degree of conversion of plant materials to a substrate and its incomplete saccharification (example 2); and as a result, a high yield of ethylene is not achieved, due to the complex effect of low yield and concentration of ethanol, high content of C3 alcohols in it. The high content of C3 alcohols in ethanol leads to the deactivation of the ethylene production catalyst (Example 2).

A high acid concentration, a long processing time and preliminary saccharification lead to a low yield and concentration of ethanol obtained due to undesired hydrolysis of hemicelluloses and cellulose (example 16), and as a result, a high ethylene yield is not achieved, due to the complex effect of low yield and low ethanol concentration there are C3 alcohols in it. The low content of C3 alcohols in ethanol leads to a decrease in the yield of ethylene due to an increase in the yield of by-products (Example 16). In addition, with a high concentration of acid there is an increased consumption of a chemical reagent, and a high duration of processing and saccharification increases the overall duration of the process and increases the risk of contamination by extraneous microflora.

A low concentration of ethanol (less than 90%) after distillation, high (above 10800 1 / h) and low (below 9400 1 / h) gas load on the catalyst lead to low productivity of the process for ethylene (examples 2, 16), low efficiency of use of equipment high specific consumption of the catalyst. To obtain ethanol with a concentration above 96%, significant costs are required for removing water from the azeotropic mixture, in addition, a high concentration of ethanol reduces the life of the catalyst.

The present invention implements an environmentally friendly closed loop technology. It uses waste from alcohol production - bard and water after distillation of the mash, waste from ethylene production - water with residual ethanol dissolved in it (examples 4-15). This allows for technological integration of flows, to reduce energy costs for the endothermic process of producing ethylene, to achieve high completeness of the use of biomass, ethanol and water, to eliminate the formation of effluents and waste. In the absence of technological integration of waste from the production of alcohol and ethylene, energy costs increase, the completeness of the use of biomass, water and ethanol decreases (examples 1-3), and effluents and waste appear.

Claims (4)

1. A method of producing ethylene from non-renewable plant raw materials, characterized in that it includes grinding the raw material, the preliminary chemical treatment of which is carried out with a solution of nitric acid with a concentration of 3-6% at a temperature of 90-95 ° C and atmospheric pressure for 3-6 h, preliminary saccharification is carried out for 18-24 hours, the combined process of saccharification and fermentation, as a result of which a mash is obtained, which is subjected to distillation and ethanol with a concentration of 90-96 m is obtained ace %, which contains impurities calculated on anhydrous ethanol C3 alcohols not more than 7 g / l, and preferably not more than 3.5 g / l, preferably not more than 0.7 g / l, but not less than 0.1 g / l, sodium ions of not more than 0.01 mg Eq / L, the ethanol obtained is sent to a catalytic reactor, where it is dehydrated to obtain a reaction gas containing ethylene, residual ethanol and water vapor, from which the ethylene gas phase is isolated, and the dehydration obtained after the reactor ethanol a liquid phase containing water with residual ethanol dissolved in it is mixed with the stream mash and sent to distillation, and water after distillation is used to prepare a solution of nitric acid of the required concentration, and the waste of alcohol production - bard - is sent to combustion and heat generation, followed by its use in the endothermic process of ethanol dehydration to ethylene. 2. The method according to p. 1, characterized in that as a non-renewable plant-based raw material for plants, Miscanthus sacchariflorus, or giganteus, or sinensis, or purpurascens is used, or oat fruit shells or mixtures thereof in any percentage ratio are used. 3. The method according to PP. 1, 2, characterized in that as an ethanol dehydration catalyst, an alumina catalyst is used, 4. The method according to PP. 1, 2, characterized in that the catalytic process of ethanol dehydration is carried out at a temperature of 375-400 ° C, a pressure of 0.11 MPa and a gas load of ethanol on the catalyst, i.e. the ratio of the hourly velocity of the ethanol gas stream at the inlet of the reactor (l / h) to the volume of the catalyst loaded in the reactor (l), 9400-10800 1 / h.

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